A Systemic-Functional Analysis Of ECST Discourse

In recent years, with the fast development of science and technology, scientific discourse plays more and more important role in people's daily lives especially in their scientific activities. Owing to the international popularity of its language, EST (English for Science and Technology) discourse particularly draws worldwide attention. EST falls into two categories, ESST (English for Specialized Science and Technology) and ECST (English for Common Science and Technology). The former one is quite specialized, written for experts in specific field, while the latter is widely used in nearly all areas. The contents of ECST discourse are less specialized and functions as conveying common scientific information to the potential readers. In this thesis, the author mainly talks about ECST discourse about the description of physical objects. For many years studies on ECST discourse are mainly on lexis and grammar, cognitive linguistics, stylistics, systemic-functional grammar (mainly on one aspect of it), or its practical use such as writing and translation. Researches on ECST from the perspective of three metafunctions proposed by Halliday are few. However, any language, no matter what cultural background it is in, has three metafunctions i.e. ideational function, interpersonal function and textual function, which are interrelated with each other. They form the three strands of meaning that any text in context is supposed to express. In this thesis, we analyze ten ECST texts in the style of description of physical objects from the perspective of three metafunctions of language proposed by Halliday. In the course of analysis, the forms of language and its functions (or meanings) are related with each other to demonstrate the special linguistic features in this particular type of ECST discourse.Based on previous findings, this study mainly applies Halliday's systemic-functional grammar as the theoretical framework, within which transitivity system, mood system and thematic system are adopted to analyze ten ECST texts of description of physical objects to demonstrate the specific linguistic features of this type of ECST discourse .Through elaborate analysis and discussion, we have got the following findings: (1) Material and relational processes appear much more frequently, and the other four types of processes do not occur at all as far as transitivity is concerned in this particular type of ECST discourse. (2) All the clauses are declarative ones. The simple present tense is more frequently used. Occasionally, a few of modal Adjuncts appear to express a kind of expectation of the author. Besides these linguistic features, some modal finites realized by modal operators also can be found in this type of ECST discourse, which serve to show the author's tentative attitude towards his representation and to display a kind of objectivity for his writing as well . (3) Most of Themes are unmarked and they are filled by nominal groups and some of them are constituted by demonstrative pronouns rather than personal pronouns. (4)Textual Theme appears frequently and plays much more important role in textual cohesion. (5) As for the TP (Thematic Progression) pattern, the constant Theme pattern is principal and the linear one next to it. From these findings, we can come to the conclusion that ECST discourse in the style of description of physical objects possesses its own specific linguistic features in terms of transitivity, mood and thematic systems within three metafunctions of language and these features are determined by the content and function of this type of ECST discourse.The study offers a perspective for analyzing and understanding of other types of discourse. This thesis particularly reveals that there are certain patterns of information distribution in this particular type of ECST discourse, as well as the semantic relations between components in a clause. These serve to the realization of coherence and cohesion of discourse. On this basis, we can get a comprehensive and better understanding of this type of ECST discourse.